For security protection of subjects to which restriction of access is desirable, a major requirement is individual accountability of persons gaining such access. User identification and authentication are prime requirements in effecting this individual accountability.
A password-based user authentication mechanism, with the password being kept secret at all times has advantages over key cards.
It is desirable to have a user when seeking access to a restricted subject to use a keyboard and generate the electronic signals that authenticate the user and result in access. The disadvantage to such manual operation of a selective sequence of keys on the keyboard is its vulnerability to detection by mere observation.
A keyboard is defined as a plane which is partitioned into M*N elements where "M" is the number of rows and "N" is the number of columns.
In a specific embodiment herein these M*N elements consist of a push button and an 8 segment light emitting diodes or liquid crystal display, and represented by Kij in the expression, matrix position coefficient.
It is an object to preserve the confidentiality of the process of entering the data by actuation of a keyboard, and preventing an observer from detecting the access code by watching a user operate the keyboard and by displaying the character in an apparent random but in fact predetermined arrangement a distraction factor is introduced.
The object of the invention is means for entering a code of characters into a system for identification and authentication which performs a comparison by a procedure which so enciphers the coded information as it is entered into the system and displayed on a keyboard as to prevent disclosure of the code by observation of the keyboard display.